if you try to simulate moonlets, it turns out there's a very narrow set of parameters where you have million-year stability. i appreciate anton's attention to detail, but moons not having rings is one of the solar system facts that surprises me the the least
My thought is that Iapetus (Saturn's moon) had rings that it pulled onto its surface as its equatorial ridge. In a similar way that Pan (another Saturn moonlet) accreted rind material around its equator. Edit: And once again I posted before I finished watching the video.
The weird thing about Japetus is that the equatorial ring only extends thru the clearly colored side, it stops abruptly when reaching the dark colored side.Besides, the clear side is the one facing forward, whereas the dark one is facing back in its orbit. The "former rings" hypothesis has trouble explaining this asymmetrical distribution of the bulge, as well as the ying-yang coloration. Further, the equatorial bulge is not small: those are fully fledged mountains 3km average height, some as tall as 5km. Flankly, Iapetus is the only object in the solar system i'd concede looks artificial in origin, way too weird. Oh, did i mentioned it's not semi spherical, but rather has angular edges? As though it were a giant crystal of sorts
You can't have a moon revolving around another moon. Parent body gravity trumps child gravity. I can't be the only human being capable of basic logic. This is too obvious. This is one of those things where my basic faith in humanity is being shaken.
@@MaxSMoke777 Troll detected. How come there are probes on stable orbits around the Moon then? Or how come planets can have moons if they orbit a star which in turn orbits a galactic center? By your logic, there cannot be any solar systems in a galaxy as the center gravity trumps all others.
No carcinogens added information and a unbreakable principle makes me think Anton is a very evolved AI experiment grown in a sand box dish. Have you noticed he doesn't age.
(1) Rings require rotation of non tidally locked bodies. (2) Rings are always perpendicular to the axis of rotation. There are no rings on any celestial body that violate 1 and 2. Spinning and frame dragging are the forces that shape rings.
That was my first thoughts to the question. Most all moons are tidally locked to the rotating planet. Why do Moons not have moons. If we consider planets as satellites of the sun (moons) then Moons do have moons, The only notable difference is rotation or being tidally locked. < I guess that would lead into a question of; What happens if a planet becomes tidally locked to the sun? :)
I find myself wondering if, after our species has died off (we certainly will have left behind a plethora of space debris and satellites), particularly shiny rings of precious metals and polished steel will eventually coalesce?
I haven't heard the video or read the paper yet, so it'll be interesting to hear their explanation. My thinking is that it's due to small SOI. Long time (50 years) since I studied celestial mechanics and relativity, but I think frame dragging is unrelated. Interested on your take.
@@axle.student I do know that the hunt for exo- planets is improving to the accuracy of hunting for exo-moons. I suspect that they will not find any tidally locked exo-planets with exo-moons. I suspect that red dwarf stars that have planets in the habitable zones will all be tidally locked, have no moons, and have no rings.
Rings around our Moon world most likely only last under a thousand years due to the uneven mass distribution in the lunar crust. It’s probably the same case for a lot of other moons.
*2 Hypotheses: A:* Moons change their orbits over time (mostly a slow down via the moon tidally "kneading" their host planet), and the rings have gaps with forbidden orbital periods (shown at 6:44). Maybe the change of the moon's orbits would just push these forbidden periods all the way through the rings and sweep the rings out of the moon's Hill sphere or into the moon's surface (7:41). (And any material swept _out of_ the moon's Hill sphere would also lead to changes in the moon's orbit - slowing it down faster, in fact.) *B:* That Iapetus ridge spawned a second idea: Have those simulations included the fact that moons can be (compared to planets) much more non-spherical? I.e. the disks would also get disturbed from mountains and valleys on the moons. The only exceptions would be liquid or gaseous moons with at most really small rocky cores. Those _have_ to have a perfect gravitational field. But also moons whose rotation has been tidally locked for most of their existence; there the disturbance from geological masses happens on the same period(s) as the disturbance from the host planet; I don't know if the signs happen be such that these disturbances can cancel. Maybe that's the explanation how that one exo-moon can have rings. Rhea (that one moon in the solar system that has a ring remnant) is both; perfectly round (though rocky) and tidally locked.
I would imagine its far more complex than we think, the complexity of gravitational fields around objects like Jupiter and Saturn are such that modelling them accurately is all but impossible with current computer systems. Our Moon is unlikely to have had rings due to its size and the proximity of Earth - bear in mind that it was significantly closer to Earth in the past and technically it orbits within Earth's outermost atmospheric envelope, the exosphere. Now this is virtually a vacuum, but in the past it may have been significantly denser when the Moon was closer - this would have an impact on particles ejected from impacts.
I don't recall if Anton ever mentioned once in that video the related question about moons having moons. I think that's an important aspect because to the best of my knowledge, there are no moons with moons either and I'd expect that to be more common than rings. But we've already seen very small objects like asteroids that have their own moons. Clearly there's a problem with orbits within orbits that makes them too unstable to persist. HOWEVER - Planets are the equivalent of moons in relation to their stars and those DO have moons and so it's an issue of relative scale. The Sun's pull on our Moon is only strong enough to keep it's orbit in the plane of the solar system but not strong enough to compete with Earth's gravity. Like rings, I think moons come and go because there's no such thing as a permanent orbit, all orbits degrade and moons will either fall into their host planet or fly off into interstellar space or an orbit of it's own around the Sun. For that reason, I believe it's very likely that interstellar space has go a LOT more rogue planets and moons roaming around than we currently suspect.
Thanks for the video. I thought that I'd seen a video on Saturn's rings moons a few years ago and that the presenter, possibly you, mentioned that it was thought that the rings were rubble remnants of a moon and that in time the rings could coalesce reforming into a moon again, or something along those lines. All this to say that a somewhat similar idea may have already been out there before this paper.
Ahh,,, back to the wonderful person goodness of Anton's thinking and sanity. A wonderful goodness, of person. Later in time, after we master living and working in space, we will be on many many moons all over the solar system.
Before seeing the video: I would guess it’s because the host planet’s gravity with regards to its Roche limit dominates the moons gravity and Roche limit, and with the conservation of angular momentum, things fall into place as they do.
Another great video. Thanks. Can you please do a video on "orbital resonance", and its link to stability in our Solar System, and to the development of planetary systems around stars in general? I'm also interested in whether the apparent fact of "orbital resonances" would increase the likelihood of stable exoplanetary orbits developing out of stellar accretion discs.
Isn't this also likely the reason moons don't have submoons although theoretically possible they are highly unlikely (Extremely rare) and there are no examples that have been discovered in the solar system to date. BTW Love your videos Anton please keep producing them
At 7:40 . That ridge is because that so called moon is an ancient artificial construct from some long ago advanced civilization and the "Death Star" of StarWars fame was modeled after this object
I never gave it much thought, but I assumed that planets smaller than Neptune and Uranus didn't have the mass to support a ring system, or if there were one, it would be too thin to see.
Just gonna put this here. _The worlds can be one together Cosmos without hatred Stars like diamonds in your eyes The ground can be space (space, space, space, space) With feet marching towards a peaceful sky All the Moonmen want things their way But we make sure they see the sun Goodbye, Moonmen We say goodbye, Moonmen Goodbye, Moonmen Goodbye, Moonmen Oh, goodbye Cosmos without hatred Diamond stars of cosmic light Quasars shine through endless nights And everything is one in the beauty And now we say goodbye, Moonmen We say goodbye, Moonmen Goodbye, Moonmen Goodbye, Moonmen Oh, goodbye_
My assumption before even watching this is that moons don't have their own moons and the gravity of the planets outweigh the gravity of their moons so therefore any debris would be attracted to the planet instead...
This is what I was thinking… moons orbit larger objects. So it’s always a gravity competition between a lesser mass and larger mass object, with the larger mass object absorbing anything that would have been in the moon’s orbit. That’s my guess at least.
Exactly. People and objects aboard the ISS experience zero-g only because there isn't much distance between the side closer to the Earth, and the side further away. So the differential in Earth's microgravity aboard the ISS is negligible. But if we were to build the ISS out to where it's tens of km wide, the outer parts would want to orbit the Earth significantly slower than the inner parts dues to differences in Earth's gravity. So any ring orbiting the ISS would experience substantial destabilizing forces which makes the ring particles want to orbit the planet rather than the moon. Obviously once you get far enough from the parent body, the gravity differential with distance decreases. Eventually allowing the formation of rings. Jupiter and Saturn are essentially "moons" orbiting the sun. They just orbit far enough away that the sun doesn't destabilize their rings.
@@solandri69 I'm also leaning towards that the satellite has to be far enough away from the parent that it's not tidally locked...Mercury is mostly tidally locked and has no moons.
I would assume that the destruction that has to occur to form visible rings is enormous. Just the fact that all that matter is floating on a somewhat singular plane. It alludes to the sheer size of whatever made it. So it's hard to see that a bunch of smaller impacts could make a ring. At least one that's visible and detectable. Oh I guess that's another thing too. For all the dust you see that makes the Rings of Saturn. There's probably a lot that you don't see. Oh duh of course there was, they discovered them during the Cassini mission right? I think.
The pictures seem to indicate that rings would be very close to the moons. What would the timescale be for small particles to be removed from these rings by Poynting-Robertson drag or the Yarkovsky effect?
Wouldn't ejecta from a cryovolcano need to have an initial velocity that's at least orbital velocity and at most escape velocity to enter an orbit around the moon? And wouldn't the "three-body problem" tend to destabilize objects orbiting a moon?
My first guess is to have rings you have to be far enough from the parent body that rings don't come near legrunge points, and you have to have a very regular surface where the moon's shape doesn't wreck orbits. Our Moon actually has no stable orbits because you're either too close to Lunar mountains/craters or too close to the Earth
Have you tried washing it inside out? That's how we used to wash screen printed shirts back in the day. The other clothes rubbing against them in the washer and dryer work to scrub the prints off.
I guess the Hill Spheres of (most) moons are just too small. Rings might form around moons, but the gravitational influence of their parent planets and/or of other moons keeps them from being permanent.
Luna is lumpy. Her gravity field is irregular, with bumps and holes. Most Lunar orbits decay quickly. So rings around Luna would be short lived. That doesn't explain the lack of rings around other moons tho.
I have seven rings in my bathtub. On Earth we should change the status of all our space junk to "moons," that way the Earth will have the most moons in our solar system.
Before seeing the rest of the vid id guess the planets the moons orbit have a stronger gravitational attraction than the moons the ejector would be expected to orbit. The lower debri would either be ejected by the moon or quickly fall onto its surface. The rest would be drawn to the planet said moons orbit, to either form rings there or be devoured by the planet.. 🤷♂️
This is analogous to the question: "Why do moons not have their own moons?" > I expect that tidal forces are going to favour the most dominant mass. That being said if we consider the sun, and the planets as satellites (moons) of the sun, then why do the the suns moons have moons. > Something else to consider is that most moons of planets are tidally locked and not rotating [Edit: On there axis][Edit: Relative to the planet they are orbiting]. Planets rotate (rings) moons do not rotate [Edit" on their axis relative to the planet]. . I guess that would lead into a question of; What happens if a planet becomes tidally locked to the sun? :)
Tidally locked does NOT mean a moon (or planet) is not rotating! It means the planet or moon is rotating on its axis exactly once per orbit. Just like our own Moon rotates once on its axis every orbit, in essentially the same orientation as its orbit, which is why we see the same side facing us all the time.
@@axle.student You are still being misleading. Again: tidally locked planets or moons ARE rotating. One only needs to look at the Pluto - Charon system to see that! Both are locked to each other. Both are rotating - as CLEARLY shown by the New Horizons probe on approach!
@@BrendanBurwood "You are still being misleading." The term "Tidally locked" explains itself. It DOES NOT rotate relative to the planet. It is locked in an exact sync with the planets rotation. That is relativity. If you want to press it even further the moon[s] (satellites) don't even travel a circular path as they travel through a straight line in space. Again that is just relativity. > if you wish to use Newtonian orbital mechanics it is described a little differently, but does not change any concept of correctness.
Just for completeness in case you are still bothered by it. The moon does not rotate on it's axis relative to Earth, But it DOES rotate on it's axis relative to our central star (The Sun).
Why does titan have a thick atmosphere and large size is it it's orbit. I tried to look pictures of the orbits of the gas giant moons and couldn't find in pictures of their orbits
Can’t speak for systems but here in the Sol system are pretty clear. If you orbit the Sun you are allowed to have rings but you don’t have to if you are orbiting something else, forget it! The planets you orbit just won’t have. 🤔
Here's an intriguing question that has NEVER been answered in all of scientific history: why is the sky high? I double dare you to take this one on, anton!
Ouriool is the bras amd the alchemie stone symontainiusley at the same time to explore the behavieures of multy diversity of manivistations of creation
If the collision theory is correct (it most likely is), then yes, that is exactly how the moon formed. The debris field settled into rings, and then some larger remnants in those rings started to snowball until ultimately coalesing into the moon.
I know there are a bunch of moons that orbit Neptune very very far away from the planet. So far away that those moons experience the greatest hill sphere from their parent planet due to their distance from the sun and nearest planets. If any moons still have rings they would be there.
